JP7206988B2 - Ink, inkjet printing device and inkjet printing method - Google Patents

Description

The present invention relates to an ink, an inkjet printing apparatus and an inkjet printing method.

Inkjet printers have advantages such as low noise, low running costs, and easy color printing, and are widely used in general households as digital signal output devices.
Some ink jet printers are used for printing on recorded matter as in the case of laser printers, but the ink jet method has the problem that the ink tends to permeate the recording medium, making it difficult to achieve high image density. In order to increase the image density, a technique of specifying the composition of pigments (Patent Document 1), a technique of increasing the viscosity of ink (Patent Document 2), and the like have been proposed. The image density can also be increased by increasing the ratio of the pigment in the ink, but in that case, the storage stability and ejection stability of the ink are lowered, resulting in a trade-off relationship.
In recent years, there is also a method of adding a large amount of fixing resin in order to improve fixing performance due to high production and compatibility with various media. performance is reduced, resulting in a trade-off relationship.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ink that has good fixability, does not impair image quality, and can improve image density.

The above problem is solved by the following configuration 1).
1) An ink containing water, an organic solvent, a pigment, and hollow resin particles having a glass transition temperature (Tg) of -30°C or higher and lower than 30°C .

According to the present invention, it is possible to provide an ink that has good fixability, does not impair image quality, and can improve image density.

FIG. 1 is a perspective explanatory view showing an example of an inkjet recording apparatus. FIG. 2 is a perspective explanatory view showing an example of a main tank in the inkjet recording apparatus. FIG. 3 is a diagram for explaining an inkjet printer used in the examples.

Hereinafter, embodiments of the present invention will be described in more detail.
The ink of the present invention is characterized by containing water, an organic solvent, a pigment, and hollow resin particles having a glass transition temperature (Tg) of −60° C. or higher and 60° C. or lower.

The hollow resin particles used in the ink of the present invention have a role as a fixing resin. If the Tg of the hollow resin particles is less than −60° C., the stickiness of the resin and the resistance to solvents will deteriorate, resulting in poor fixability (spreadability) and ejection stability. On the other hand, if the Tg exceeds 60° C., the resin will not be sufficiently dissolved during fixing, which will adversely affect fixability (scratch resistance), image density and color. The Tg of the hollow resin particles is preferably −53° C. or higher and 56° C. or lower, more preferably −30° C. or higher and lower than 30° C., from the viewpoint of further improving fixability, ejection stability and image density. .

Moreover, the hollow resin particles used in the ink of the present invention preferably have a hydrophobic group. In such a form, since the hollow resin particles can be uniformly dispersed with the pigment, it is possible to suppress density unevenness and density decrease, which is preferable.

In addition, from the viewpoint of improving fixability and suppressing ejection failure and maintenance failure, the solid content concentration of the hollow resin particles in the ink is preferably 5% by mass or more and 10% by mass or less. When the solid content concentration of the hollow resin particles in the ink is 5% by mass or more, the function of the hollow resin particles as a binder resin that binds the pigments together can be exhibited, and fixability can be improved. Further, when the content is 10% by mass or less, it is possible to suppress an increase in the viscosity of the ink and to suppress the occurrence of ejection failures and maintenance failures, which is preferable.

Moreover, from the viewpoint of improving fixability and suppressing a decrease in pigment concentration and color unevenness, the average particle size (volume average particle size) of the hollow resin particles is preferably 50 nm or more and 500 nm or less. By setting the average particle size of the hollow resin particles to 50 nm or more, the hollow resin particles function as a binder resin that binds the pigments together. Good dispersion is maintained, and a decrease in pigment concentration and color unevenness can be suppressed, which is preferable.

In addition, from the viewpoint of improving the fixability and increasing the image density, the mass ratio of the pigment to the hollow resin particles should be 0.8 or more and 1.5 or less when the pigment is 1. is preferred. By setting the ratio to 0.8 or more, the function of the hollow resin particles as a binder resin that binds the pigments together can be exhibited, and fixability can be improved. A high image density can be obtained by setting the ratio to 1.5 or less, which is preferable.
A more preferable ratio is 1.0 or more and 1.3 or less for the hollow resin particles when the pigment is taken as 1.

<Example of structural analysis of resin>
The structure of the resin contained in the ink can be analyzed by the following means.
FT-IR measurement FT-IR spectrum measurement is performed using an FT-IR spectrometer (manufactured by PerkinElmer, trade name "Spectrum One"), 16 scans, resolution: 2 cm ^-1 , mid-infrared region (400 cm ^-1 −4000 cm ⁻¹ ).

An example of NMR measurement After dissolving a sample in deuterated chloroform at a concentration as high as possible, the solution is placed in a 5 mmφ NMR sample tube and subjected to various NMR measurements. JNM-ECX-300 manufactured by JEOL Resonance is used as a measuring device.
The measurement temperature is 30° C., and the ¹ H-NMR measurement is performed with 256 integration times and a repetition time of 5.0 sec. The ¹³ C measurement is performed with 10,000 cumulative times and a repetition time of 1.5 sec. It is possible to assign the component from the obtained chemical shift and calculate the compounding ratio from the numerical value obtained by dividing the integrated value of the corresponding peak by the number of protons or carbons.
When performing more detailed structural analysis, it is also possible to perform double quantum filter 1H-1H shift correlation two-dimensional NMR measurement (DQF-COSY), etc. In this case, the number of integration times is 1,000, and the repetition time is 2. Although the coupling state, that is, the reaction site can be specified from the spectrum obtained by conducting the reaction at 0.45 sec or 2.80 sec, it can be sufficiently distinguished by ordinary 1H and 13C measurements.

GC/MS measurement A reaction pyrolysis gas chromatograph-mass spectrometry (GC/MS) method using a reaction reagent is performed. The reaction reagent used is a 10% by mass methanol solution of tetramethylammonium hydroxide (TMAH) (manufactured by Tokyo Chemical Industry Co., Ltd.). The GC-MS device is QP2010 manufactured by Shimadzu Corporation, the data analysis software is GCMSsolution manufactured by Shimadzu Corporation, and the heating device is Py2020D manufactured by Frontier Lab.
〔Analysis conditions〕
・ Reactive pyrolysis temperature: 300°C
-Column: Ultra ALLOY-5, L = 30 m, ID = 0.25 mm,
Film = 0.25 µm
・Column temperature rise: 50°C (holding for 1 minute) to 10°C/min to 330°C (holding for 11 minutes)
・Carrier gas pressure: 53.6 kPa constant ・Column flow rate: 1.0 mL/min
・Ionization method: EI method (70 eV)
・Mass range: m/z, 29-700
・Injection mode: Split (1:100)

<Example of qualitative and quantitative methods for organic solvents>
The structure of the organic solvent contained in the ink can be analyzed by the following means.
GC/MS measurement Qualitative analysis is performed by pyrolysis gas chromatography-mass spectrometry (GC/MS) or by diluting with a solvent such as THF and removing pigments by centrifugation. MS) method. A quantitative value can be obtained by preparing a calibration curve for the material to be quantified and performing the same evaluation.
〔Analysis conditions〕
・Column: DB-35MS, L=60m, ID=0.25mm, Film=0.25μm
・Column temperature rise: 50°C (holding for 1 minute) to 10°C/min to 250°C (holding for 5 minutes)
・Column flow rate: 1.0 mL/min
・Ionization method: EI method (70 eV)
・Mass range: m/z, 18-700
・Injection mode: Split (1:50)

<Ink>
Organic solvents, water, pigments, resins, additives, etc. used in the ink are described below.

<Organic solvent>
The organic solvent used in the present invention is not particularly limited, and any water-soluble organic solvent can be used. Examples thereof include polyhydric alcohols, ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, and sulfur-containing compounds.
Specific examples of water-soluble organic solvents include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, and 1,4-butane. Diol, 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol , 2,4-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl- Polyhydric alcohols such as 1,3-pentanediol and petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl Polyhydric alcohol alkyl ethers such as ethers, polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone , 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, nitrogen-containing heterocyclic compounds such as γ-butyrolactone, formamide, N-methylformamide, N,N-dimethylformamide, 3-methoxy-N,N- Amides such as dimethylpropionamide and 3-butoxy-N,N-dimethylpropionamide, amines such as monoethanolamine, diethanolamine, and triethylamine, sulfur-containing compounds such as dimethylsulfoxide, sulfolane, and thiodiethanol, propylene carbonate, and ethylene carbonate. etc.
It is preferable to use an organic solvent having a boiling point of 250° C. or less because it not only functions as a wetting agent but also provides good drying properties.

Polyol compounds having 8 or more carbon atoms and glycol ether compounds are also preferably used. Specific examples of polyol compounds having 8 or more carbon atoms include 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol.
Specific examples of glycol ether compounds include polyhydric alcohol alkyls such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether. Ethers; polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, and the like.

A polyol compound having 8 or more carbon atoms and a glycol ether compound can improve ink permeability when paper is used as a recording medium.

The content of the organic solvent in the ink is not particularly limited and can be appropriately selected according to the purpose. 20% by mass or more and 60% by mass or less is more preferable.

<Water>
The content of water in the ink is not particularly limited and can be appropriately selected according to the purpose. % to 80% by mass is more preferred.

<Pigment>
An inorganic pigment or an organic pigment can be used as the pigment. These may be used individually by 1 type, and may use 2 or more types together. Mixed crystals may also be used. Pigments are preferred for producing density on the recording medium.
Examples of pigments that can be used include black pigments, yellow pigments, magenta pigments, cyan pigments, white pigments, green pigments, orange pigments, glossy color pigments such as gold and silver, and metallic pigments.
As inorganic pigments, in addition to titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, and chrome yellow, carbon black produced by known methods such as contact method, furnace method, thermal method, etc. can be used.
Organic pigments include azo pigments, polycyclic pigments (e.g., phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinoflurone pigments, etc.). , dye chelates (eg, basic dye chelates, acid dye chelates, etc.), nitro pigments, nitroso pigments, aniline black, and the like. Among these pigments, those having good affinity with the solvent are preferably used. In addition, resin hollow particles and inorganic hollow particles can also be used.

Specific examples of pigments for black include carbon blacks (C.I. Pigment Black 7) such as furnace black, lamp black, acetylene black and channel black, or copper and iron (C.I. Pigment Black 11). , metals such as titanium oxide, and organic pigments such as aniline black (C.I. Pigment Black 1).
Further, for color, C.I. I. Pigment yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104 , 108, 109, 110, 117, 120, 138, 150, 153, 155, 180, 185, 213, C.I. I. Pigment Orange 5, 13, 16, 17, 36, 43, 51, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48:2, 48:2 (Permanent Red 2B (Ca)), 48:3, 48:4, 49:1, 52: 2, 53:1, 57:1 (brilliant carmine 6B), 60:1, 63:1, 63:2, 64:1, 81, 83, 88, 101 (red red), 104, 105, 106, 108 ( cadmium red), 112, 114, 122 (quinacridone magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 184, 185, 190, 193, 202, 207, 208, 209, 213, 219, 224, 254, 264, C.I. I. Pigment Violet 1 (rhodamine lake), 3, 5:1, 16, 19, 23, 38, C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue), 15:1, 15:2, 15:3, 15:4 (phthalocyanine blue), 16, 17:1, 56, 60, 63, C.I. I. Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, etc.

The content of the pigment in the ink is preferably 0.1% by mass or more and 15% by mass or less, more preferably 1% by mass or more and 10% by mass or less, from the viewpoints of improving image density, good fixability, and ejection stability. is.

In order to disperse the pigment in the ink, a method of introducing a hydrophilic functional group into the pigment to make it a self-dispersing pigment, a method of coating the surface of the pigment with a resin and dispersing it, a method of dispersing using a dispersant, etc.
As a method of making a self-dispersing pigment by introducing a hydrophilic functional group into a pigment, for example, a self-dispersing pigment that is dispersible in water by adding a functional group such as a sulfone group or a carboxyl group to a pigment (for example, carbon). can be used.
As a method for dispersing the pigment by coating the surface of the pigment with a resin, a method in which the pigment is encapsulated in microcapsules and dispersible in water can be used. This can be rephrased as a resin-coated pigment. In this case, all the pigments mixed in the ink need not be coated with a resin, and uncoated pigments or partially coated pigments may be dispersed in the ink as long as the effects of the present invention are not impaired. may be
Examples of the method of dispersing using a dispersant include a method of dispersing using a known low-molecular-weight dispersant and high-molecular-weight dispersant typified by surfactants.
As the dispersant, it is possible to use, for example, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc. depending on the pigment.
A dispersing agent may be used individually by 1 type, or may use 2 or more types together.

<Pigment dispersion>
Inks can be obtained by mixing materials such as water and organic solvents with pigments. Ink can also be produced by mixing a pigment, water, a dispersant, and the like to form a pigment dispersion, and then mixing materials such as water and an organic solvent.
The pigment dispersion is obtained by dispersing water, a pigment, a pigment dispersant, and optionally other components, and adjusting the particle size. Dispersion should be carried out using a disperser.
The particle diameter of the pigment in the pigment dispersion is not particularly limited, but the dispersion stability of the pigment is improved, and the image quality such as ejection stability and image density is improved. 500 nm or less is preferable, and 20 nm or more and 150 nm or less is more preferable. The particle size of the pigment can be measured using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).
The content of the pigment in the pigment dispersion is not particularly limited and can be appropriately selected according to the purpose. % or more and 50 mass % or less is preferable, and 0.1 mass % or more and 30 mass % or less is more preferable.
The pigment dispersion is preferably degassed by filtering coarse particles with a filter, a centrifugal separator, or the like, if necessary.

<Hollow resin particles>
The ink of the present invention contains hollow resin particles having a glass transition temperature (Tg) of −60° C. or higher and 60° C. or lower.

The glass transition temperature (Tg) in the present invention can be measured using a differential scanning calorimeter such as Thermo plus EVO2 (manufactured by Rigaku) or Q-2000 type temperature modulated DSC (manufactured by TA Instruments Co., Ltd.). . Specifically, the measurement is performed under the conditions of the following continuous temperature programs 1 to 3, and the value measured by the temperature program 3 is taken as the glass transition temperature. The reason why the measurement is performed in the temperature program and the measured value of the temperature program 3 is used is to ensure the reproducibility of the measured value.
Temperature program:
1. 2. Temperature rise from -80°C to 150°C at a rate of 10°C/minute and hold for 1 minute 2. Cool from 150°C to -80°C at a cooling rate of 10°C/minute and hold for 1 minute 3. Heat up from -80 to 150°C at a heating rate of 10°C/min

The type of resin used for the hollow resin particles is not particularly limited and can be appropriately selected depending on the purpose. Examples include urethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, Butadiene-based resins, styrene-butadiene-based resins, vinyl chloride-based resins, acrylstyrene-based resins, acrylsilicone-based resins, and the like can be mentioned.

The hollow resin particles preferably contain a resin having a hydrophobic group. Examples of the hydrophobic group include, but are not limited to, an alkyl group and a benzyl group.

Ink can be obtained by mixing the hollow resin particles with a material such as a pigment or an organic solvent in a resin emulsion state in which water is used as a dispersion medium. The hollow resin particles may be used singly, or two or more hollow resin particles may be used in combination.

The volume average particle diameter of the hollow resin particles is not particularly limited and can be appropriately selected depending on the intended purpose. 30 nm or more and 500 nm or less is more preferable, and 50 nm or more and 500 nm or less is preferable. The volume average particle diameter can be measured, for example, using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

The particle size of the solid content in the ink is not particularly limited and can be appropriately selected according to the purpose. is preferably 20 nm or more and 1000 nm or less, more preferably 20 nm or more and 150 nm or less. The solid content includes resin particles, pigment particles, and the like. The particle size can be measured using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

Hollow resin particles may be appropriately synthesized or may be commercially available. The method for synthesizing the hollow resin particles is not particularly limited and can be appropriately selected according to the purpose. An emulsion polymerization method is preferred in which a hollow resin particle emulsion is formed by stirring while stirring.

Examples of the vinyl monomer include nonionic monofunctional ethylenically unsaturated monomers, difunctional vinyl monomers, and trifunctional or higher vinyl monomers. These may be used individually by 1 type, and may use 2 or more types together.
Examples of the nonionic monofunctional ethylenically unsaturated monomers include styrene, vinyl toluene, ethylene, vinyl acetate, vinyl chloride, vinylidene chloride, acrylonitrile, (meth)acrylamide, and (meth)acrylic acid ester. These may be used individually by 1 type, and may use 2 or more types together. Among these, (meth)acrylic acid esters are preferred. Examples of the (meth)acrylic acid ester include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, benzyl (meth)acrylate, ) acrylate, lauryl (meth)acrylate, oleyl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate and the like.
Examples of the bifunctional vinyl monomer include divinylbenzene, allyl (meth) acrylate, ethylene glycol di (meth) acrylate, 1,5-butanediol di (meth) acrylate, diethylene glycol di (meth) acrylate, and the like. .
Examples of the tri- or higher-functional vinyl monomer include trimethylolpropane tri(meth)acrylate.
By copolymerizing the nonionic monofunctional ethylenically unsaturated monomer with at least one of the difunctional vinyl monomer and the trifunctional or higher-functional vinyl monomer and highly cross-linking, not only light scattering properties but also heat resistance are improved. Hollow resin particles having properties such as toughness, solvent resistance and solvent dispersibility can be obtained.

Any surfactant may be used as long as it forms molecular aggregates such as micelles in water. Examples thereof include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. is mentioned. These may be used individually by 1 type, and may use 2 or more types together.
As the polymerization initiator, a known water-soluble compound can be used, and examples thereof include hydrogen peroxide and potassium persulfate. These may be used individually by 1 type, and may use 2 or more types together.
Examples of the aqueous dispersion medium include water and water containing a hydrophilic organic solvent.

The hollow resin particles have, for example, a hollow inner layer and an outer layer made of a resin. The outer diameter of the outer layer is preferably 50 nm or more and 500 nm or less, and the inner diameter of the inner layer is preferably 50 nm or more and 300 nm or less. .

<Additive>
Surfactants, antifoaming agents, antiseptic antifungal agents, anticorrosive agents, pH adjusters, etc. may be added to the ink as necessary.

<Surfactant>
Any of silicone surfactants, fluorine surfactants, amphoteric surfactants, nonionic surfactants, and anionic surfactants can be used as surfactants.

The silicone-based surfactant is not particularly limited and can be appropriately selected depending on the purpose. Among them, those that do not decompose even at high pH are preferable. Those having an oxyethylene group or a polyoxyethylene polyoxypropylene group are particularly preferred because they exhibit good properties as water-based surfactants. As the silicone-based surfactant, a polyether-modified silicone-based surfactant can also be used, and examples thereof include compounds in which a polyalkylene oxide structure is introduced into the side chain of the Si portion of dimethylsiloxane.

Examples of fluorine-based surfactants include perfluoroalkylsulfonic acid compounds, perfluoroalkylcarboxylic acid compounds, perfluoroalkylphosphoric acid ester compounds, perfluoroalkylethylene oxide adducts, and perfluoroalkyl ether groups in side chains. Polyoxyalkylene ether polymer compounds are particularly preferred due to their low foaming properties. Examples of the perfluoroalkylsulfonic acid compound include perfluoroalkylsulfonic acid and perfluoroalkylsulfonate. Examples of the perfluoroalkylcarboxylic acid compounds include perfluoroalkylcarboxylic acids and perfluoroalkylcarboxylic acid salts. As the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in a side chain, a sulfate ester salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in a side chain, and a perfluoroalkyl ether group in a side chain Examples thereof include salts of polyoxyalkylene ether polymers. Counter ions of salts in these _{fluorosurfactants} include Li, Na, K, _NH4 , _NH3CH2CH2OH , _{NH2 ( CH2CH2OH} ) ₂ , and _{NH ( CH2CH2OH} ). ₃ and the like.

Examples of amphoteric surfactants include laurylaminopropionate, lauryldimethylbetaine, stearyldimethylbetaine, lauryldihydroxyethylbetaine and the like.

Nonionic surfactants include, for example, polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyoxyethylene propylene block polymers, sorbitan fatty acid esters, polyoxyethylene sorbitan Examples include fatty acid esters and ethylene oxide adducts of acetylene alcohol.
Examples of anionic surfactants include polyoxyethylene alkyl ether acetates, dodecylbenzene sulfonates, laurates, and salts of polyoxyethylene alkyl ether sulfates.
These may be used individually by 1 type, or may use 2 or more types together.

The silicone-based surfactant is not particularly limited and can be appropriately selected depending on the intended purpose. Examples include polydimethylsiloxane modified at both chain ends, and polyether-modified silicone-based surfactants having polyoxyethylene groups or polyoxyethylene-polyoxypropylene groups as modifying groups exhibit excellent properties as water-based surfactants. preferable.

As such a surfactant, an appropriately synthesized one may be used, or a commercially available product may be used. Commercially available products are available from, for example, BYK Chemie Co., Ltd., Shin-Etsu Chemical Co., Ltd., Dow Corning Toray Silicone Co., Ltd., Nihon Emulsion Co., Ltd., Kyoeisha Chemical Co., Ltd., and the like.

The above polyether-modified silicone-based surfactant is not particularly limited and can be appropriately selected according to the purpose. Examples include those introduced into the side chain of the Si portion of siloxane.

(However, m, n, a, and b in general formula (S-1) represent integers. R and R' represent an alkyl group and an alkylene group.)

Commercially available products can be used as the above polyether-modified silicone-based surfactants. 1906EX (Japan Emulsion Co., Ltd.), FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, FZ-2164 (Dow Corning Toray Silicone Co., Ltd.), BYK-33, BYK-387 (BYK-Chemie Corporation), TSF4440, TSF4452, TSF4453 (Toshiba Silicon Co., Ltd.) and the like.

As the fluorosurfactant, a fluorine-substituted compound having 2 to 16 carbon atoms is preferable, and a fluorine-substituted compound having 4 to 16 carbon atoms is more preferable.

Examples of fluorine-based surfactants include perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in side chains. Among these, polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group in the side chain are preferable because of their low foamability, and in particular, fluorine-based compounds represented by general formulas (F-1) and (F-2) Surfactants are preferred.

In the compound represented by the general formula (F-1), m is preferably an integer of 0 to 10 and n is preferably an integer of 0 to 40 in order to impart water solubility.

General formula (F-2)
_{CnF2n +1-} CH2CH(OH) _{CH2 -} O-( _CH2CH2O ) _{a -} Y

In the compound represented by the above general formula (F-2), Y is H, or CmF _2m+1 and m is an integer of 1 to 6, or CH ₂ CH(OH)CH ₂ -CmF _2m+1 and m is 4 to 6 Integer, or CpH _2p+1 where p is an integer from 1-19. n is an integer of 1-6. a is an integer from 4 to 14;

Commercially available products may be used as the fluorosurfactant.
Examples of commercially available products include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (all manufactured by Asahi Glass Co., Ltd.); Fleurard FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (both manufactured by Sumitomo 3M); Megafac F-470, F -1405, F-474 (both manufactured by DIC); Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR (both manufactured by DuPont); FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW (both manufactured by Neos Co., Ltd.), Polyfox PF-136A, PF-156A, PF-151N, PF- 154, PF-159 (manufactured by Omnova Co., Ltd.), Unidyne DSN-403N (manufactured by Daikin Industries, Ltd.), etc. Among these, good print quality, especially color development, permeability to paper, wettability, and level dyeing FS-300 manufactured by Du Pont, FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW manufactured by Neos Co., Ltd., FT-400SW manufactured by Omnova Co., Ltd. Polyfox PF-151N and Unidyne DSN-403N manufactured by Daikin Industries, Ltd. are particularly preferred.

The content of the surfactant in the ink is not particularly limited and can be appropriately selected according to the purpose. % or more and 5 mass % or less is preferable, and 0.05 mass % or more and 5 mass % or less is more preferable.

<Antifoaming agent>
The antifoaming agent is not particularly limited, and examples thereof include silicone antifoaming agents, polyether antifoaming agents, and fatty acid ester antifoaming agents. These may be used individually by 1 type, or may use 2 or more types together. Among these, silicone-based antifoaming agents are preferred because of their excellent foam breaking effect.

<Preservative and antifungal agent>
The antiseptic and antifungal agent is not particularly limited, and examples thereof include 1,2-benzisothiazolin-3-one.

<Antirust agent>
The rust inhibitor is not particularly limited, and examples thereof include acidic sulfites and sodium thiosulfate.

<pH adjuster>
The pH adjuster is not particularly limited as long as it can adjust the pH to 7 or higher, and examples thereof include amines such as diethanolamine and triethanolamine.

The physical properties of the ink are not particularly limited and can be appropriately selected depending on the intended purpose. For example, viscosity, surface tension, pH and the like are preferably within the following ranges.
The viscosity of the ink at 25° C. is preferably 5 mPa·s or more and 30 mPa·s or less, more preferably 5 mPa·s or more and 25 mPa·s or less, from the viewpoint of improving the print density and character quality and obtaining good ejection properties. more preferred. Here, the viscosity can be measured using, for example, a rotational viscometer (RE-80L manufactured by Toki Sangyo Co., Ltd.). Measurement conditions are 25° C., standard cone rotor (1°34′×R24), sample liquid volume 1.2 mL, rotation speed 50 rpm, 3 minutes.
The surface tension of the ink is preferably 35 mN/m or less, more preferably 32 mN/m or less at 25° C., from the viewpoint that the ink is appropriately leveled on the recording medium and the drying time of the ink is shortened.
The pH of the ink is preferably from 7 to 12, more preferably from 8 to 11, from the viewpoint of preventing corrosion of metal members in contact with the liquid.

<Pretreatment liquid>
The pretreatment liquid contains a flocculant, an organic solvent, and water, and may optionally contain a surfactant, an antifoaming agent, a pH adjuster, an antiseptic agent, an antirust agent, and the like.
Organic solvents, surfactants, antifoaming agents, pH adjusters, antiseptic antifungal agents, and antirust agents can be the same materials as those used for inks, and other materials used for known treatment liquids can be used. .
The type of flocculant is not particularly limited, and examples thereof include water-soluble cationic polymers, acids, polyvalent metal salts, and the like.

<Post-treatment liquid>
The post-treatment liquid is not particularly limited as long as it can form a transparent layer. The post-treatment liquid is obtained by selecting and mixing organic solvents, water, resins, surfactants, antifoaming agents, pH adjusters, antiseptic antifungal agents, anticorrosive agents, etc., as necessary. Further, the post-treatment liquid may be applied to the entire recording area formed on the recording medium, or may be applied only to the area where the ink image is formed.

<Recording medium>
The recording medium used for recording is not particularly limited, but includes plain paper, glossy paper, special paper, cloth, film, OHP sheet, general-purpose printing paper, and the like.
The recording medium is not limited to those used as general recording media, and wallpaper, floor materials, building materials such as tiles, cloth for clothing such as T-shirts, textiles, leather, and the like can be used as appropriate. Ceramics, glass, metal, etc. can also be used by adjusting the configuration of the path for conveying the recording medium.

<Records>
The ink recorded matter of the present invention has an image formed on a recording medium using the ink of the present invention.
A recorded matter can be obtained by recording with an inkjet recording apparatus and an inkjet recording method.

The inkjet printing apparatus of the present invention includes the ink of the present invention, an ejection mechanism for ejecting the ink onto a printed material to obtain a printed material, and a heating mechanism for heating the printed material. It has a fixing mechanism for fixing onto the printed material.
Further, the inkjet printing method of the present invention has an ejection step of ejecting the ink of the present invention onto a material to be printed to obtain a printed matter. It further includes a fixing step of applying pressure to the printed matter and fixing it on the printed matter.
Specific examples of the inkjet printing apparatus and printing method of the present invention are described below.

<Recording device, recording method>
The ink of the present invention can be suitably used for various inkjet recording apparatuses, such as printers, facsimile machines, copiers, printer/facsimile/copier complex machines, stereolithography machines, and the like.
In the present invention, a recording apparatus and a recording method refer to an apparatus capable of ejecting ink, various treatment liquids, and the like onto a recording medium, and a method of performing recording using the apparatus. A recording medium means a medium to which ink or various processing liquids can adhere even temporarily.
This recording apparatus can include not only a head portion for ejecting ink, but also means for feeding, conveying, and discharging a recording medium, and other devices called pre-processing devices and post-processing devices. .
The recording apparatus and recording method may have heating means used in the heating process and drying means used in the drying process. The heating means and drying means include, for example, means for heating and drying the printing surface and the back surface of the recording medium. The heating means and drying means are not particularly limited, but for example, hot air heaters and infrared heaters can be used. Heating and drying can be performed before, during, or after printing.
Also, the recording apparatus and recording method are not limited to those that visualize significant images such as characters and graphics with ink. For example, it includes those that form patterns such as geometric patterns, and those that form three-dimensional images.
In addition, unless otherwise specified, the recording apparatus includes both a serial type apparatus in which the ejection head is moved and a line type apparatus in which the ejection head is not moved.
Furthermore, this recording device can be used not only as a desktop type, but also as a wide recording device that can print on A0 size recording media, and for example, can use continuous paper wound into a roll as a recording medium. A continuous feed printer is also included.

An example of a recording apparatus will be described with reference to FIGS. 1 and 2. FIG. FIG. 1 is a perspective explanatory view of the device. FIG. 2 is a perspective explanatory view of the main tank. An image forming apparatus 400 as an example of a recording apparatus is a serial image forming apparatus. A mechanical unit 420 is provided inside the exterior 401 of the image forming apparatus 400 . Each ink container 411 of the main tank 410 (410k, 410c, 410m, 410y) for each color of black (K), cyan (C), magenta (M), and yellow (Y) is packed with, for example, an aluminum laminated film. It is made up of members. The ink containing portion 411 is housed, for example, in a container case 414 made of plastic. Thus, the main tank 410 is used as an ink cartridge for each color.
On the other hand, a cartridge holder 404 is provided on the far side of the opening when the cover 401c of the apparatus main body is opened. A main tank 410 is detachably attached to the cartridge holder 404 . As a result, each ink discharge port 413 of the main tank 410 communicates with the ejection head 434 for each color via the supply tube 436 for each color, and ink can be ejected from the ejection head 434 onto the printing medium.

This recording apparatus can include not only a portion that ejects ink, but also devices called pre-processing devices and post-processing devices.
As an aspect of the pre-treatment device and the post-treatment device, it has a pre-treatment liquid and a post-treatment liquid in the same manner as in the case of inks such as black (K), cyan (C), magenta (M), and yellow (Y). There is a mode in which a liquid container and a liquid ejection head are added, and the pretreatment liquid and the posttreatment liquid are ejected by an inkjet recording method.
As another aspect of the pre-treatment device and the post-treatment device, there is an aspect in which a pre-treatment device and a post-treatment device using a method other than the inkjet recording method, such as a blade coating method, a roll coating method, and a spray coating method, are provided.

It should be noted that the method of using the ink is not limited to the ink jet recording method, and can be widely used. In addition to the inkjet recording method, for example, a blade coating method, a gravure coating method, a bar coating method, a roll coating method, a dip coating method, a curtain coating method, a slide coating method, a die coating method and a spray coating method can be used.

The use of the ink of the present invention is not particularly limited and can be appropriately selected according to the intended purpose. Furthermore, it can be used not only as an ink to form two-dimensional characters and images, but also as a three-dimensional modeling material for forming a three-dimensional three-dimensional image (three-dimensional object).

A known three-dimensional modeling apparatus for forming three-dimensional objects can be used, and is not particularly limited. be able to. The three-dimensional object includes a three-dimensional object obtained by applying ink repeatedly. It also includes a molded product obtained by processing a structure obtained by applying ink onto a base material such as a recording medium. The molded product is, for example, a sheet-shaped or film-shaped recorded matter or structure that has been subjected to molding such as heat stretching or punching.・Suitably used for applications where molding is performed after the surface is decorated, such as electronic equipment, meters for cameras, and operation panels.

In the present invention, the terms image formation, recording, printing, and printing are all synonymous.
The terms recording medium, medium, and printed material are all synonymous.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to Examples. However, the present invention is not limited by these examples. In addition, unless otherwise specified, ink preparation and evaluation were performed under the conditions of room temperature of 25° C. and humidity of 60%.

<Preparation of hollow resin particles A>
(1) Synthesis of seed particle emulsion
Deionized water (726.0 parts by weight), methyl methacrylate (5.0 parts by weight), and methacrylic acid (0.00 parts by weight) were added to a four-necked separable flask equipped with a stirrer, thermometer, condenser, and dropping funnel. 1 part by mass) was charged and heated with stirring. Then, when the internal temperature in the separable flask reached 70° C., a 10% by mass ammonium persulfate aqueous solution (1.0 parts by mass) was added and heated at 80° C. for 20 minutes.
On the other hand, methyl methacrylate (141.0 parts by mass), methacrylic acid (94.9 parts by mass), sodium alkylbenzene sulfonate as an anionic emulsifier (trade name: Neogen SF-20, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., 25. 0 parts by mass) and deionized water (120.0 parts by mass) were emulsified with a homodisper to form a pre-emulsion, and then charged into a dropping funnel.
Next, while maintaining the internal temperature in the separable flask at 80° C., the obtained pre-emulsion was uniformly added dropwise over 2 hours, and at the same time, a 10% by mass ammonium persulfate aqueous solution (10.0 parts by mass) was added. It was dripped uniformly over 2 hours. After completion of dropping, the mixture was aged at 80° C. for 2 hours, cooled and filtered using a 120-mesh filter cloth to obtain a seed particle emulsion A.

(2) Synthesis of hollow resin particles A Seed particles obtained by charging deionized water (188.2 parts by mass) into a four-necked separable flask equipped with a stirrer, thermometer, cooler, and dropping funnel. Emulsion A (70.0 parts by mass) was added dropwise and heated to 80° C. while stirring.
On the other hand, butyl acrylate (140 parts by mass), sodium alkylbenzene sulfonate (trade name: Neogen SF-20, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., 5.0 parts by mass), and deionized water (55.3 parts by mass) was emulsified with a homodisper to obtain pre-emulsion 1, and then charged into a dropping funnel.
Furthermore, while maintaining the internal temperature in the separable flask at 80° C., the obtained pre-emulsion 1 was uniformly added dropwise over 30 minutes, and at the same time, a 10% by mass sodium persulfate aqueous solution (1.2 parts by mass) was added. was dropped uniformly over 30 minutes.
Methyl methacrylate (125 parts by mass), styrene (14 parts by mass), sodium alkylbenzenesulfonate (trade name: Neogen SF-20, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., 5.0 parts by mass), and deionized water (51. 8 parts by mass) was emulsified with a homodisper to obtain a pre-emulsion 2, which was put into a dropping funnel. Then, while maintaining the internal temperature of the separable flask at 80° C., one hour after the completion of dropping the pre-emulsion 1, the obtained pre-emulsion 2 was uniformly dropped over 60 minutes, and at the same time, A 10% by mass sodium persulfate aqueous solution (3.5 parts by mass) was uniformly added dropwise over 60 minutes.
After dropping pre-emulsion 2, 28% by mass aqueous ammonia (7.5 parts by mass) was dropped to swell and dissolve the seed particles, followed by aging at 80° C. for 1 hour. After cooling, the mixture was filtered using a 120-mesh filter cloth to obtain hollow resin particles A having a solid content concentration of 20% by mass.

<Hollow Resin Particles B to E, Hollow Resin Particle I>
In the preparation of hollow resin particles A, a hollow resin was prepared in the same manner as in the preparation of hollow resin particles A, except that the amounts of butyl acrylate (BA), methyl methacrylate (MMA), and styrene (St) were changed to the parts by weight shown in Table 1. Particles BE and hollow resin particles I were prepared.

<Hollow resin particles H>
Deionized water (188.2 parts by mass) was charged into a four-necked separable flask equipped with a stirrer, a thermometer, a condenser, and a dropping funnel to obtain seed particle emulsion A (70.0 parts by mass). was added dropwise and heated to 80° C. with stirring.
On the other hand, n-lauryl methacrylate (280 parts by mass), sodium alkylbenzene sulfonate (trade name: Neogen SF-20, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., 10 parts by mass), and deionized water (110 parts by mass) were homogenized. After emulsifying with a disper to obtain pre-emulsion 1, it was put into a dropping funnel.
Furthermore, while maintaining the internal temperature in the separable flask at 80 ° C., the obtained pre-emulsion 1 was uniformly added dropwise over 60 minutes, and at the same time, 10% by mass sodium persulfate aqueous solution (5 parts by mass) was added to 60%. It was dripped evenly over a period of minutes.
After dropping pre-emulsion 1, 28% by mass aqueous ammonia (7.5 parts by mass) was dropped to swell and dissolve the seed particles, and the mixture was aged at 80° C. for 1 hour. After cooling, the mixture was filtered using a 120-mesh filter cloth to obtain hollow resin particles H having a solid content concentration of 20% by mass.

<Intermediate resin particles F>
Synthesis of seed particle emulsion F
Deionized water (726.0 parts by weight), methyl methacrylate (5.0 parts by weight), and methacrylic acid (0.00 parts by weight) were added to a four-necked separable flask equipped with a stirrer, thermometer, condenser, and dropping funnel. 1 part by mass) was charged and heated with stirring. Then, when the internal temperature of the separable flask reached 70°C, a 10% by mass ammonium persulfate aqueous solution (1.0 part by mass) was added and heated at 80°C for 20 minutes.
On the other hand, methyl methacrylate (141.0 parts by mass), methacrylic acid (94.9 parts by mass), sodium alkylbenzene sulfonate (trade name: Neogen SF-20, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., 20.0 parts by mass) as an anionic emulsifier. 0 parts by mass) and deionized water (120.0 parts by mass) were emulsified with a homodisper to form a pre-emulsion, and then charged into a dropping funnel.
Next, while maintaining the internal temperature of the separable flask at 80°C, the obtained pre-emulsion was uniformly added dropwise over 3 hours, and at the same time, a 10% by mass ammonium persulfate aqueous solution (10.0 parts by mass) was added. It was dripped uniformly over 3 hours. After completion of the dropwise addition, the mixture was aged at 80° C. for 3 hours, cooled and filtered using a 120-mesh filter cloth to obtain a seed particle emulsion F.
Hollow resin particles F were obtained in the same manner as hollow resin particles A were prepared.

<Hollow resin particles G>
Synthesis of seed particle emulsion G
Deionized water (726.0 parts by weight), methyl methacrylate (5.0 parts by weight), and methacrylic acid (0.00 parts by weight) were added to a four-necked separable flask equipped with a stirrer, thermometer, condenser, and dropping funnel. 1 part by mass) was charged and heated with stirring. Then, when the internal temperature of the separable flask reached 70°C, a 10% by mass ammonium persulfate aqueous solution (1.0 part by mass) was added and heated at 80°C for 20 minutes.
On the other hand, methyl methacrylate (141.0 parts by mass), methacrylic acid (94.9 parts by mass), sodium alkylbenzenesulfonate (trade name: Neogen SF-20, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., 30.0 parts by mass) as an anionic emulsifier. 0 parts by mass) and deionized water (120.0 parts by mass) were emulsified with a homodisper to form a pre-emulsion, and then charged into a dropping funnel.
Next, while maintaining the internal temperature of the separable flask at 80°C, the obtained pre-emulsion was uniformly added dropwise over 1 hour, and at the same time, 10% by mass ammonium persulfate aqueous solution (10.0 parts by mass) was added. was uniformly added dropwise over 1 hour. After completion of dropping, the mixture was aged at 80° C. for 1.5 hours, cooled and filtered using a 120-mesh filter cloth to obtain a seed particle emulsion G.
Hollow resin particles G were obtained in the same manner as hollow resin particles A were prepared.

Table 1 shows the Tg and volume average particle diameter of each hollow resin particle.

<Black Pigment Dispersion B1>
20 parts by mass of an organic solvent (methyl ethyl ketone), 0.03 parts by mass of a polymerization chain transfer agent (2-mercaptoethanol), 15 parts by mass of methacrylic acid as a polymerization initiator and monomers, 30 parts by mass of a styrene monomer, 20 parts by mass of benzyl methacrylate, Using 10 parts by mass of polyethylene glycol monomethacrylate (EO = 15), 10 parts by mass of polypropylene glycol monomethacrylate (PO = 9), and 15 parts by mass of styrene macromonomer, 75 0.9 parts by mass of 2,2'-azobis(2,4-dimethylvaleronitrile dissolved in 40 parts by mass of methyl ethyl ketone per 100 parts by mass of the monomer component is added and aged at 80°C for 1 hour. to obtain a polymer solution.
The obtained polymer solution was dried under reduced pressure, and 5 parts by mass of the obtained solution was dissolved in 15 parts by mass of methyl ethyl ketone, and the polymer was neutralized using an aqueous sodium hydroxide solution. Further, 15 parts by mass of carbon black was added, and the mixture was kneaded with a disperser while adding water. After adding 100 parts by mass of ion-exchanged water to the resulting kneaded product and stirring, methyl ethyl ketone is removed at 60° C. under reduced pressure, and a part of the water is removed to obtain a black pigment having a solid content concentration of 20% by mass. A water dispersion (pigment dispersion B1) was obtained.

<Ink preparation>
Example 1
Materials (parts by mass) having the formulation shown in Table 2 were mixed and stirred, and then filtered through a membrane filter having an average pore size of 0.8 μm to obtain an ink. Parts are parts by weight. In Table 2, Safinol is a nonionic surfactant manufactured by Air Products Co., Ltd., and ENVIROGEM is an antifoaming agent manufactured by Nissin Chemical Industry Co., Ltd.

Examples 2-9, Comparative Examples 1-2
Inks of Examples 2 to 9 and Comparative Examples 1 and 2 were obtained by repeating Example 1 except that the formulations in Example 1 were changed to those shown in Table 2.

<Evaluation method>
The inks of Examples 1 to 9 and Comparative Examples 1 and 2 were evaluated using the inkjet printing apparatus shown in FIG.

In FIG. 3, this apparatus is a serial type inkjet recording apparatus, and includes a printing unit 101 that prints on the print medium 2, a transport unit 102 that transports the print medium 2, a roll storage unit 103 that stores the print medium 2, and a print medium 2. A roll take-up unit 104 for taking up the tape is provided.
This apparatus uses a roll body 1 in which a printing medium 2 as a medium is wound in a roll shape. The roll body 1 is stored in the roll storage part 103, and the print medium 2 is pulled out from the roll body 1 by the conveying roller 31 and sent out.
The printing unit 101 has three or more liquid ejection heads 11 for ejecting liquid mounted on a carriage 12 . The carriage 12 is held by a guide member 13 so as to be reciprocatable in the main scanning direction (the direction perpendicular to the paper surface in FIG. 1). Here, the head 11 and the carriage 12 constitute a liquid ejection unit 110 .
The head 11 has, for example, one or a plurality of nozzle rows that eject liquids of respective colors such as black (K), yellow (Y), magenta (M), cyan (C), and white (W). The above heads 11 are arranged side by side. Further, the head 11 is integrally provided with a sub-tank for supplying liquid.
The carriage 12 is also equipped with detection means for detecting the width of the print medium 2 .
The conveying unit 102 has a conveying roller 21 and a counter roller 22 arranged upstream of the printing unit 101 in the medium conveying direction (the direction of arrow A), and conveys the print medium 2 while sandwiching it. Also, a platen member 25 that guides the print medium 2 is arranged so as to face the printing unit 101 .
The roll take-up unit 104 includes a take-up roll 41 for taking up the print medium 2 .
A pre-heater 51 , a print-heater 52 , and a post-heater 53 are arranged along the transport direction of the print medium 2 .
The preheater 51 is a heater that heats the print medium 2 before the printing area of the printing unit 101 . The print heater 52 is a heater as heating means for heating the print medium 2 in the printing area of the printing unit 101 . The post-heater 53 is a heater as heating means for heating the print medium 2 after printing by the printing unit 101 . For the pre-heater 51, the print heater 52, and the post-heater 53, electric heaters using ceramic or nichrome wire can be used.
A hot air fan 54 for blowing hot air onto the print medium 2 is provided downstream of the post heater 53 . A hot air fan 54 blows hot air directly onto the liquid on the printing surface to lower the humidity of the atmosphere and dry it completely.

・Printing conditions Image resolution: 600 x 600dpi
Adhesion amount of ink: 10 mg/cm ²
Chart: Betta
Heating temperature: 60°C Setting media: GIY-11Z5 (Lintec polyvinyl chloride sheet)

[Printing Evaluation 1 Image Density]
The printed image was measured with X-Rite (manufactured by X-Rite) to measure each density.
Evaluation criteria are as follows.
◎: 1.35 or more ○: 1.25 or more and less than 1.35 Δ: 1.20 or more and less than 1.25 ×: less than 1.20 Table 3 shows the evaluation results.

[Print evaluation 2 fixability (scratch resistance)]
The printed image was scratched with a fingernail to evaluate the image. The evaluation criteria were as follows.
⊚: No image deviation is observed.
◯: Image deviation cannot be visually confirmed.
Δ: Slight image deviation is visually observed, but within the allowable range.
x: Image deviation is clearly recognized and is out of the allowable range.
Table 3 shows the evaluation results.

[Printing Evaluation 3 Fixability (Spreadability)]
After 3 hours or more have passed after printing, a white cotton cloth (manufactured by Toyo Seiki Co., Ltd.) mounted on a crockmeter (manufactured by Toyo Seiki Co., Ltd.) is reciprocated 10 times for a solid image portion, and the ink stains adhering to the white cotton cloth are visually observed. It was observed and evaluated according to the following criteria.
Judgment criteria ◎: No dirt
○: Stained, but practically no problem
Δ: Slightly noticeable stains ×: Significant stains observed Table 3 shows the evaluation results.

From Table 3, the ink of each example contains water, an organic solvent, a pigment, and hollow resin particles having a glass transition temperature (Tg) of −60° C. or higher and 60° C. or lower. It has been found that the image density can be improved without impairing the image quality.

400 Image forming apparatus 401 Exterior of image forming apparatus 401c Cover of apparatus main body 404 Cartridge holder 410 Main tank 410k, 410c, 410m, 410y For black (K), cyan (C), magenta (M), and yellow (Y) main tank 411 ink storage unit 413 ink discharge port 414 storage container case 420 mechanism unit 434 ejection head 436 supply tube 1 roll body 2 print medium 11 liquid ejection head 12 carriage 13 guide member 21 transport roller 22 counter roller 25 platen member 31 transport Roller 41 Take-up roll 51 Pre-heater 52 Print heater 53 Post-heater 54 Hot air fan 101 Printing unit 102 Conveying unit 103 Roll storage unit 104 Roll winding unit

JP-A-2000-290548 JP 2006-16412 A

Claims (10)

An ink comprising water, an organic solvent, a pigment, and hollow resin particles having a glass transition temperature (Tg) of -30°C or higher and lower than 30°C . 2. The ink according to claim 1 , wherein the hollow resin particles are hollow resin particles having a hydrophobic group selected from an alkyl group and a benzyl group . 3. The ink according to claim 1, wherein the hollow resin particles in the ink have a solid content concentration of 5% by mass or more and 10% by mass or less. 4. The ink according to any one of claims 1 to 3 , wherein the hollow resin particles have an average particle size of 50 nm or more and 500 nm or less. 5. Any one of claims 1 to 4 , wherein the weight ratio of the hollow resin particles to the pigment is 0.8 or more and 1.5 or less when the pigment is 1. Ink as described. 6. The ink according to any one of claims 1 to 5, wherein the pigment is a white pigment. 7. The ink according to any one of claims 1 to 6, wherein the pigment is titanium oxide. An inkjet printing apparatus comprising: the ink according to any one of claims 1 to 7 ; an ejection mechanism for ejecting the ink onto a printed material to obtain a printed material; and a heating mechanism for heating the printed material. An inkjet printing method comprising the step of ejecting the ink according to any one of claims 1 to 7 onto a printed material to obtain a printed material. The inkjet printing method according to claim 9 , further comprising a heating step of heating the printed material.

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